Shoe outsole sewing machine



Jan. 25, 1955 F. AsHwoRTl-l 2,700,350

sHoE oUTsoLE SEWING MACHINE Filed sept. 10, 1952 sheets-sheet 1 Invenlior' /T/"ed 45m/Offb N w s vJam. 25, 1955 F. AsHwoR'TH 2,700,350

SHOE oUTsoLE SEWING MACHINE Filed Sept.` 10, 1952 2 Sheets-Sheet 2 Med/8.......

f-eed.- feed, v Frewa' Fool? ack Cam CL' 5 Inventor: Tg Fred s//wO/f/r du n fo r SHE UTSOLE SEWING `MACHINE Fred Ashworth, Wenham, Mass., lassignor. to United Shoe Machinery Corporation, Flemington,N. J., la corporation of New Jersey Application September kl0, 1952,Serial No. 308,805

6 Claims. (Cl. 112-60) The present invention `relates to shoe outsole sew-ing machines and more particularly `to improvements in'such machines intended for inserting -stitches of extremely uniform ornamental appearance with their Vexposed threads lying in accurate alinement along the surface of the work in a manner corresponding to that disclosed in United States Letters Patent No. 2,644,412, granted'luly 7, 1953, in the name of the present inventor, this type of operation being commonly designated as .fine white stitching to distinguish it from a saw toothfa-ppearance often found in non-ornamental scams The machine of Patent No. 2,644,412 above referred to is a lockstitch welt shoe sole sewing machine of the type disclosed in United States Letters 'Patent 'No. 2,271,611 vgranted February 3, 1942, upon an application of the present inventor and Carl F. Whitaker, and No. 2,337,631 granted December `28, 1943 upon an application of Carl F. Whitaker.

In the machine of Patent No. 2,644,412 the construction of the work support is such that the lengths of thread in a seam exposed along the surface of the work lie in accurate alinement from one stitch to another. `For assisting in bringing the exposed ythread lengths :into accurate alinement, the work support in the machine -of Patent No. 2,644,412 is provided with a seam alining shoulder running along the work engaging surface of the work support from a needle receiving opening inthe work support. The operator, in guiding a' lshoefthrou'gh the machine, causes the Vexposed threads in the completed portion of the seam to be pressed against the shoulder. Pressure of the presser foot on the shoe ,while clamping it enhances the action of the shoulder on the work support in alining the exposed .thread :lengths ,of vthe inserted seam. However, excessive pressure'of ,the presser foot against the shoe is a disadvantage Vin a machine in which the Work is fed while clamped, between the work support and presser foot, it being necessary to twist and turn a shoe while ybeing sewed rto present its projecting sole edges properly to the stitch forming devices. lf the clamping pressure on the work support is excessive, the operator will have great difficulty properly presenting the shoe, particularly about abrupt `curyatures around the sole edge and .there will b e'a strong tendency for the sole edge to be ejected by the pressure from the grip of the Work support and ,presser foot.

lt is an object of the present invention to provide a shoe outsole sewing machine having work clamping and feeding work support and presser footrnechanism in which a suitable clamping action may be .obtained by the presser foot and work support on the work for the purpose of inserting a seam with its exposed thread lengths in accurate alinement to conform with requirements for inserting line white stitching, without the natural disadvantages ordinarily met when excessive Work clamping pressure is employed. Other objects are to improve the operation of a machine of the type, referred to. in a manner which will enable insertion of tighter stitches more accurately and uniformly than heretofore regardless of whether iine white stitching orl other class of seam is being inserted. To these ends the illustrated machine has a needle, an awl, a take-up and other stitch forming devices actuated from a main sewing'- shaft and a work feeding clamp including a work support and a presser foot, the latter of which is actuated against the work with an increased or supplemental clampingpressure, greater than at any other time during, each sewing cycle,

States Patent ICC from a time just before each stitch is tightened and set until after Athe awl penetrates the work for a new stitch to its fullest extent, after which time the presser foot is disengaged from the work. By imparting a greater clamping pressure only during lthe interval of a sewing cycle noted and discontinuing the clamping pressure before the needle penetrates `the Work and during the remainder of the sewing cycle, the ladvantage of a clamp feeding machanism is retained without the natural disadvantage resulting from clamping the work substantiallythroughout'the sewing cycle with an excessivepressure, the period of ysupplemental pressure of the presser Ifoot on the work `being terminated before the clamp is back fed and the Vpresser' foot re-en'gages the work. During the remainder of the sewing cycle a reduced pressure is exerted suicient only to 'insure proper Work feed without interfering'with the turning or other shoe positioning movements thereof.

These land other features of the invention vrelate to novel and improved constructions vvof clampfeedmechanisrn 4cooperating in'a particularly advantageous manner with the vpresser foot while lexerting its greatest clamping-pressure on the'wor-k and to other devices, combinations and-arrangements of parts hereinafter dcscribedand claimed, the advantages of which will readilybe understood by one skilled inthe art'from the following 'detailed specication taken in connection with 'the accompanying drawings, in which: n

AFig. 1 is a View in side lelevation of kparts .of amachine embodying the features of thepresentlinvention` and :illustrating Vparticularly the work support, kpresser foot, feed carriage and actuating ymecahnisms therefor, together with a shoe being operated upon, vshown in section;

5Fig. 2 is a fragmentary view in front elevation on an enlarged scale showing a section through the line of a seam beinginserted-in 'a shoe;

Fig. 3 is a plan View of the feed carriage vand its actuating mechanism in the machine illustrated in Fig. 1;

Fig. v4 is a detail sectional View on an enlarged scale taken along the line IV-IV of Fig. `3; and

Pig. 5 is a chart illustrating the time relations of some of the stitch Iforming and presser foot actuating mechanisms in the machine.

The machine illustrated in the drawings is of the type disclosed in the United States Letters Patent above noted and in No. 2,354,729, granted August l, 1944 'on application of Fred Ashworth `et al. The machine is a lock-stitch `shoe outsole stitching machine provided with a curved 'hook needle 2, a shuttle 4, a curved awl '6, 'a rotary ytake-up 7 (Fig. 2) for tightening and setting each stitch in the work, and other stitch forming devices actua-ted by mechanism driven from a main sewing shaft '8. As in prior machines the type referred to the take-up acts on the thread, indicated at 9, carried by the needle to tighten and set each stitch in the Work. Necessarily, the tension applied to the thread by the take-up is reduced `substantially by the frictional effects on the thread as it engages its guides and other surfaces over which it is led between the take-up and the work. For this reason the tension in the set stitches may fall far below the maximum to which the thread is capable of being tightened without breakage.

To increase the tension of the thread in each stitch, the present invention contemplates squeezing the work in a particularly desirable manner while each stitch is being set so that after the stitches are set the work will expand against them and tighten them more securely than is possible by the take-up alone, To enable the squeezing action of the presser foot to be increased to a point where it will be effective and to eliminate the tendency to eject the work from the grip of the work support and presser foot, the squeezing action is so timed that it will' occur only while a stitch is being set and not at such times as will cause difficulty.

The work in the present machine, as in the patented one, is secured in sewing position and is fed in the direction of the completed stitches by a clamp comprising a work support 10 and a presser foot 12. While the awl engages the work the clamp is back fed' and the presser foot is lifted to disengage the work. The Work support 10 is secured by cap screws 14 to feed carriage 16 clamped to an inclined pivot shaft 18 forming a fixed center of rotation 'A about which the carriage swings in the direction of work feed. The presser foot also is movable with the feed carriage and is secured to a lever 20 pivoted at 22 on the carriage to enable it to clamp and release the work as the carriage swings in the direction of work feed and is back ed, the work support being located at the side of the work from which the awl operates and the presser foot being located at the side of the work from which the needle operates.

To actuate the presser foot in clamping and releasing the Work, a rearwardly extending arm of the lever 28 is pivotally connected through a link 24 to one point 26 at an end of a oating lever 28, the link 24 serving as an actuating member for the presser foot. A second point 30 spaced along the length of the oating lever from the point 26 and located between the ends of the floating lever includes a pin connected to a presser foot lock. A third point 32 spaced from the point 30 on the lever 28 comprises a pivot connecting a fork-ended link 34 between the oating lever and an actuating cam lever 36 fulcrumed loosely on a shaft 38. The cam lever 36 carries a roll 40 engaging a slot having suitably curved surfaces in a cam 42 secured to the sewing shaft 8.

For convenience in connecting the floating lever 28 with the presser foot lock, the pin at 30 is secured in a motion equalizing lever 44 having one end pivoted at 4S to a pair of lugs, one on an angular arm 46 projecting from a cover plate 48 for a box 50 of the presser foot lock hereinafter to be described, and the other 51 on the frame of the machine.

At the free end of the equalizing lever 44 is a pin 52 connected through a pair of parallel links 54 to the movable members of the presser foot lock contained in the box 50. The links 54 are secured together by a bolt 56 and are pivotally connected at their lower ends to wedge members 58 slidingly mounted in the box. To lock the presser foot mechanism so that release of the work clamping pressure by the presser foot is prevented, the wedge members are clamped within the lock box by a series of rolls 60 acted upon by a locking lever 62.

For bringing the presser foot against the work during each sewing cycle with a preliminary clamping pressure there is pivotally connected to the links 54 through a C- shaped link 64 an H-shaped link 66, in turn connected with yielding means comprising a presser foot spring 68. The connections between the spring 68 and the link 66 comprise a lever 70 fulcrumed on a shaft 72, a link 74 connecting the lever 70 with a lever 76 mounted on a fixed stud 78 directly connected to one end of the presser foot spring 68. The other end of the presser foot spring is engaged with an arm 80 comprising an adjustable tensioning mechanism and having an integral horizontal shaft 82 rotatable in the machine frame to increase or decrease the force of the spring 68. On the hub of the arm 80 is a worm wheel 84, engaged with a worm on the shaft 82. The shaft 82 is provided with a thumb wheel 88 disposed at a convenient location on the machine for adjustment by the operator. Thus, the spring 68 and presser foot lock act through the connections described at -the central point 30 on the floating lever 28, the presser foot being connected to the point 26 and the cam driven actuating member 34 at the point 32.

To actuate the locking finger 62 a downwardly extending arm thereon is pivotally connected to a rod-like reduced link 90 slidingly supported on a perforated bracket 92 between which and a checknut 94 on the link 90 is compressed a relatively heavy spring 96 surrounding the link. Between the end of the link 90 is a shoulder contacted by the lower end of a cam actuated lever 98 having a roll 100 engaged with a slot formed with suitably curved surfaces in a cam on the sewing shaft 8, the lever 98 being fulcrumed on a cross shaft 102. As thus far described the machine of the present invention is similar to that of Patent No. 2,354,729.

The construction and manner of operating the presser foot mechanism in the machine of Patent No. 2,337,631 is such that at the beginning of each sewing cycle the spring corresponding to the present spring 68 acts after the presser foot is lifted to bring the presser foot yieldingly into engagement with a preliminary pressure on a Work piece disposed upon the work support. As the machine starts in operation, an increased supplemental clamping pressure is exerted by the presser foot to squeeze the work beyond that imparted to the presser foot by the spring. The supplemental clamping pressure resists the force of the awl in penetrating the work, ensures a better action when a rough rounding cutter is employed and continues until the awl has penetrated completely through the work. As soon as the awl has penetrated the work to its fullest extent the presser foot is lifted from engagement with the work and the clamp comprising the work support and presser foot are back fed a distance equal to the length of a stitch. After the work feeding clamp has been back fed, the presser foot lock is unlocked and the presser foot reengages the work yieldingly with the same preliminary spring pressure as exerted 1n starting the machine. Immediately thereafter the supplemental clamping pressure is reexerted by the presser foot with a squeezing force equal to that previously applied. This supplemental squeezing pressure is continued from the time the needle engages the work throughout the remainder of the sewing cycle for a major portion thereof until substantially the end of the sewing cycle is reached, at which time the supplemental pressure is discontinued and the preliminary pressure only is retained.

While the manner of operation of the presser foot in the machine of the Patent No. 2,337,631 is especially beneficial when a rough rounding cutter is attached to the awl carrier to trim the margin of a shoe sole while the awl is penetrating the work, the use of the supplemental work squeezing pressure tends to cause a shoe sole to be ejected from the grip of the Work support and presser foot after the needle disengages the work and the work is being fed where relatively narrow margins are provided on the sole edge. This tendency is not troublesome, however, where there is a substantial projection of the sole edge, as is common when a rough rounding cutter is employed. Thus, with ordinary work having a narrow sole edge projection, difficulty frequently is encountered by an operator in maintaining a shoe being sewn in proper sewing position.

In accordance with a feature of the present invention the benefit of supplemental work squeezing and clamping pressure applied by the presser foot to the work is retained while the awl is penetrating the work, by providing the presser foot actuating slot in the cam 42 with the proper curvature, without the usual tendency to eject the work from the grip of the work feeding clamp after the needle has disengaged the work and the work is being fed, even with a narrow projecting margin on the sole. In addition to the benefit obtained in the machine of Patent No. 2,337,631 in resisting the force of the awl in penetrating the work and in obtaining a better action with a rough rounding cutter when such is employed, the operation of the illustrated machine is improved further in that it is possible to insert tighter, more uniform stitches than heretofore obtainable with a given strength of thread. Also itis possible to actuate the presser foot with a greater work squeezing pressure while each stitch is being set than heretofore considered possible. To these ends the cam 42 of the present machine has its slot cut with a single curved and eccentric presser foot depressing portion only, which slot portion is active at the beginning of each sewing cycle to cause the presser foot to exert a supplemental squeezing pressure on the work increased beyond that imparted at any other time in the sewing cycle, as distinguished from the use of two supplemental work squeezing portions in the corresponding cam of the prior Whitaker machine. To discontinue the supplemental pressure the remainder of the slot in the cam 42 is concentric and inactive, the eccentric portion merging at its ends with the ends of the concentric portion. Furthermore, the slot of the cam 42 in the illustrated machine has its presser foot depressing portion starting earlier than that in the corresponding depressing portion of the Whitaker machine so that supplemental squeezing pressure is applied before each stitch is set in the work by the take-up and continues only until after the awl penetrates the Work to its greatest extent of entry. After the awl penetrates the work the presser foot is disengaged entirely from the work while the clamp including the presser foot and the work support are being back fed.

Referring to the time chart of Fig. 5 is will be apparent that the slot in the cam 42 is cut with the presser foot depressing portion 104 and this depressing portion is engaged with the roll from a point 10 from starting position of a sewing cycle to a point approximately at 50 of sewing shaft rotation between which points each stitch is set bythe take-up. The length of the depress,- ing portion of the cam slot thus is 40. After settlng each stitch, the take-up gives up thread and the presser foot is lifted from engagement with the work by the cam 42 until the work feeding clamp is back fed. After back feed has been completed, the presser foot and work support being returned to uniform back fed positions regardless of feed adjustments, the presser foot lock is unlocked and the spring 68 causes the presser foot to exert a preliminary clamping pressure on the work. After the preliminary clamping kpressure is applied the lock is closed to hold the presser foot in place without exerting any supplement squeeze, the cam slot having a concentric dwell therein which continues the preliminary clamping pressure until the end of the sewing cycle is substantially reached.

The increased supplemental work squeezing or clamping pressure is exerted at lthe first part of each sewing cycle only, just before each stitch is set by the take-up, and is continued beyond the position where the stitch is set until after the awl penetrates the work to its fullest extent, being discontinued while the awl engages the work and before the needle engages it. It `has been found that the time is so brief ,during which the increased supplemental pressure is exerted that there is no tendency to eject the edge of a sole from the grip of the presser foot and work support even though a relatively narrow margin is provided on the sole, the supplementary clamping pressure not being reexerted during the feed or during the remainder of the sewing cycle. Also at the time the work is squeezed it is held in place by the stitch setting tension on the thread. By continuing the supplementary clamping pressure until after the awl penetrates the work, the benefit f the squeezing action on the workis obtained both for securing an unusually tight stitch and for resisting the force of the awl, kthe thickness of the work tending to expand (Fig. 2) after the supplementary clamping pressure is released and to tighten the stitch more securely than would otherwise be possible. The benefits of secure tension in a stitch are particularly advantageous where line white stitching is being inserted since there is no opportunity for lateral displacement of the threads in the seam after each stitch is set.

As a further means for securing a uniform ornamental appearance to a seam in a manner which is particularly advantageous in line white stitching, the mechanism for actuating the feed carriage of the prior machine has been modified. In the prior machine the feed carriage is actuated in the direction of work feed while the presser foot clamps the work and in a back feed direction while the presser -foot releases the work. The feed carriage mechanism of that machine is provided with adjustable connections, including a yoke, mounted on a fixed center of rotation, and toggle links connecting the yoke with the feed carriage. The toggle links have a central pivot joint movable toward the center of rotation of the yoke while feeding the work and away from the center of rotation of the yoke while the feed carriage is being back fed. To adjust the length of work feed `so as to increase or decrease the number of stitches inserted per inch, manual connections are provided for rotating the yoke about its fixed center. The result of the arrangement in the patented machine is that the work support and presser foot always move while being fed to a uniform position regardless of the adjustment of the yoke.

As in the prior machine, the needle and awl operate in a path defining a fixed plane, not moving in the direction of feed so that the Work support moves with relation to the awl, bringing the right end of a -needle and awl receiving slot in the work support a fixed distance from the needle and awl path. While sewing with a tine white stitching adjustment in the machine it is the usual practice to bring the left end of the needle and awl receiving slot in the work support as close as possible to the needle path. The purpose of such adjustment is to cause the work support to clamp the thread in each previously formed stitch as close as possible to the needle while engaging the work so that as the threaded needle retracts from the work there will be little or no possibility of improper location of the thread carried by the needle between the clamped portion of the thread running from the last formed stitch to the stitch in the process of being formed. If the length of stitch is changed during the insertion of a seam with the prior machine, then the distance from the left end 6 of the needle opening -in the work support to the needle while engaging the-work will be increased causing avariation in thread placement on the work and disruption of the fine white stitching adjustment.

In accordance with this feature in the illustrated machine, the adjusting connections in the feed carriage -actuating mechanism are such that during the back feed of the feed carriage the work support moves to a uniform position where the left end of the needle slot is always a fixed distance from the needle while engaging the work regardless of the adjustment in the feed connections. kThis result is accomplished by a few relatively simple changes in the feed carriage actuating mechanism in which the lengths of the toggle links are varied to cause the central pivot joint of the toggle'links Yto move toward the lcenter of rotation of the yoke to which they are connected while the work support is 'being back fed and away from the center of rotation of the yoke while the feed carriage is being fed.

As shown in Figs. 3 and 4 of the drawings, a rearwardly extending arm of the carriage 16 is connected through an eccentric pin 106 with a toggle link 108` having a central pivot joint 110 with a toggle link 112. The toggle link 112 is in turn pivoted at 114 to a yoke 116 rotatable about a fixed center comprising an integral stud 118 on the yoke and a bearing 120 in the machine frame. The yoke 116 has an arm 122 pivotally connected with a link 124 connected in turn with a bell crank 126. The bell crank 126 is connected through a link 128 with a manually actuated lever 130 mounted in a convenient location near the operating point in the machine.

For actuating the central joint 110 of the toggle it is connected by a link 132 with a cam lever 134 carrying a roll 136 engaging a slot in a cam 138 on the sewing shaft 8. 'The cam lever 134 moves the central joint 110 of the toggle links toward the center of the bearing 120 in the frame to the solid line position of Figs. 3 and 4 while the feed carriage 16 is being back fed and from the center of rotation of the bearing to the broken line position while the carriage is feeding the work. ln this way the presser foot and work support are always held in their back fed position while the needle engages the work close to the edge of the needle receiving slot in the table. By so doing, the left end of the needle and awl slot closest to the last formed stitch in the work is carried as close as possible to the needle path, and the thread length 140 (Fig. 2) running from the last formed stitch to the previous stitch is clamped by the work support as close as possible to the needle while engaging the work under all conditions of adjustment in the work feed. Thus, the same benefits of the supplemental clamping and squeezing pressure of the presser foot on the work are ,obtained under feed adjustments for all lengths of stitch.

As a further advantage in the present machine the clamping pressure of the presser foot on the work during feeding movements of the work is controlled directly by manual rotation of the thumb wheel 88. Accordingly, for heavy inflexible work where a greater clamping pressure is required, an increase of preliminary pressure may be obtained by rotating the thumb Wheel and with thin soft work, reverse rotation of the thumb wheel will reduce the clamping pressure without adversely affecting the feeding action of the work clamp, which is desirable in proper location of threads and in secure tightening of each stitch in a seam. By the construction of this invention control of the clamping pressure is rendered possible while the machine is running.

The nature and scope of the invention having been indicated and a particular embodiment having been described, what is claimed is; v

l. A shoe outsole sewing machine having a sewing shaft, stitch forming devices including a needle, an awl and a take-up, a work feeding clamp comprising a work support and a presser foot, a carriage on which the work support and presser foot are mounted movable in the direction of work feed, yielding means for bringing the presser foot against the work during each sewing cycle with a preliminary clamping pressure, a member connected to the presser foot for actuating it, and a lock for preventing release of the clamping pressure of the presser foot on the work, in combination with mechanism connected to the actuating member comprising a cam on the sewing shaft cut with a curvature to increase the clamping pressure of the presser foot on the work beyond that imparted to the presser foot by the yielding means, before each stitch is set in the work by the take-up and to discontinue the increased clamping pressure of the presser foot on the work while the awl engages the work and throughout the remainder of the sewing cycle.

2. A shoe outsole sewing machine having a'sewing shaft, stitch forming devices including a needle, an awl and a take-up, work feeding clamp comprising a Work support and a presser foot, a carriage on which the work support and presser foot are mounted movable in the direction of work feed, yielding means for bringing the presser foot against the work during each sewing cycle with a preliminary clamping pressure, a member connected to the presser foot for actuating it and a lock for preventing release of the clamping pressure of the presser foot on the work, in combination with mechanism connected to the actuating member comprising a cam on the sewing shaft cut with a curvature to increase the clamping pressure of the presser foot on the work beyond that imparted to the presser foot by the yielding means, before each stitch is set in the work by the take-up and until the awl penetrates the work, the increased clamping pressure being discontinued before the needle engages the work and during the remainder of the sewing cycle.

3. A shoe outsole sewing machine having a sewing shaft, stitch forming devices actuated by the sewing shaft including a needle, an awl and a take-up, a work feeding clamp comprising a work support located at the side of the work from which the awl operates and a presser foot located at the side of the work from which the needle operates, a feed carriage upon which the work support and presser foot are mounted movable about a fixed center of rotation in the direction of work feed, yielding means for bringing the presser foot against the work during each sewing cycle with a preliminary clamping pressure, a lock for preventing release of the clamping pressure of the presser foot on the work, a member for actuating the presser foot to lift it from the work, and a floating lever having one point along its length connected to the presser foot, a second point connected to the lock and a third point connected to the actuating member, in combination with a cam on the sewing shaft for driving the actuating member cut with a curvature to increase the clamping pressure of the presser foot on the work beyond that imparted to the presser foot by the yielding means just before each stitch is set in the work by the take-up and to discontinue the increased clamping pressure while the awl penetrates the work and before the needle engages the work and throughout the remainder of the Sewing cycle and a second cam on the sewing shaft cut with a curvature to open the lock while the presser foot is disengaged from the work, the presser foot thereafter engaging the work under the force of the yielding means and to close the lock during the remainder of a sewing cycle, the presser foot driving cam being inactive to vary the pressure of the presser foot on tlliie work until just before the awl again engages the wor 4. A shoe outsole sewing machine having a sewing shaft, stitch forming devices actuated by the sewing shaft, including a needle, an awl and a take-up for tightening and setting each stitch, a work feeding clamp comprising a work support located at the side of the work from which the awl operates and a presser foot located at the side of the work from which the needle operates, a carriage upon which the work support and presser foot are mounted movable in the direction of work feed, a member for actuating the presser foot, mechanism for actuating the feed carriage in the direction of work feed while the actuating member causes the presser foot to clamp the work and in a back-feed direction while the actuating member causes the presser foot to release the work, in combination with adjustable connections in the carriage actuating mechanism provided with a yoke mounted on a Xed center of rotation and toggle links connecting the yoke and the feed carriage having a central pivot joint moving away from the center of rotation of the yoke while feeding the work and toward the center of rotation of the yoke while the carriage is being back fed.

5. A shoe outsole sewing machine having a sewing shaft, stitch forming devices actuated by the sewing shaft, including a needle, an awl and a take-up for tightening and setting each stitch, a work feeding clamp comprising a work support located at the side of the work from which the awl operates and a presser foot located at the side of the work from which the needle operates, a carriage upon which the work support and presser foot are mounted movable in the direction of work feed, yielding means for bringing the presser foot against the work during each sewing cycle with a preliminary clamping pressure, a lock for preventing release of the clamping pressure of the presser foot on the work, a member for actuating the presser foot to clamp and release the work, a oating lever having one point along its length connected to the presser foot, a second point connected to the lock and a third point connected to the actuating member, mechanism for actuating the feed carriage in the direction of work feed while the actuating member causes the presser foot to clamp the work and in a back-feed direction while the actuating member causes the presser foot to release the work, in combination with a cam on the sewing shaft for driving the actuating member cut with a curvature to increase the clamping pressure of the presser foot on the work beyond that imparted to the presser foot by the yielding means, just before each stitch is set in the work yby the take-up and to discontinue the increased pressure before the needle engages the work and for the remainder of the sewing cycle, and adjustable connections in the carriage actuating mechanism provided with a yoke mounted on a fixed center of rotation and toggle links connecting the yoke and the feed carriage having a central pivot joint moving away from the center of rotation of the yoke while feeding the Work and toward the center of rotation of the yoke while the carriage is being back fed, the needle engaging the work while the presser foot and work support are in back fed positions.

6. A shoe outsole sewing machine having a sewing shaft, stitch forming devices including a needle, an awl and a take-up, a work feeding clamp comprising a work support and a presser foot, a carriage on which the work support and presser foot are mounted movable in the direction of work feed, yielding means for bringing the presser foot against the work during each sewing cycle with a preliminary pressure, a lock for preventing release of the clamping pressure of the presser foot on the work, and a presser foot actuating lever, in combination with means operative to increase the clamping pressure of the presser foot on the work beyond that imparted to the presser foot by the yielding means and to lift the presser foot from engagement with the work comprising a cam on the sewing shaft having a single curved eccentric portion, a roll on the presser foot actuating lever engaged with said curved eccentric portion of the cam from a point before each stitch is set in the work by the take-up until the awl penetrates the work in each sewing cycle, the curved eccentric portion then merging with the concentric portlon.

References Cited in the le of this patent UNITED STATES PATENTS 2,354,729 Ashworth et al. Aug. l, 1949 2,527,196 Pederson Oc't. 24, 1950 2,580,238 Muc Dec. 25, 1951 

